Composite sandwich endplates with a compliant pressure distributor for a PEM fuel cell

Two endplates are used to fasten a proton exchange membrane fuel cell (PEMFC) stack composed of gaskets, gas diffusion layers (GDLs), membrane electrode assemblies (MEAs) and bipolar plates. The endplates should provide uniform and adequate compaction pressure to the stack components to decrease the electrical resistance of stacks and to prevent fuel leakage. It is also important to provide good thermal insulation for low heat loss and good cold-start characteristics. Therefore, an optimum endplate design is necessary to improve both the energy efficiency and reliability of the PEMFC.In this work, an insulating foam-core composite sandwich structure and a pre-curved compliant pressure distributor for the design of endplates are employed for both good insulation performance and uniform pressure distribution on the PEMFC stack. The thermal insulation, flexural rigidity, structural safety, weight and cost of the endplates were considered in the design of the composite sandwich structure. Finally, the composite sandwich endplate was developed based on the optimum design, and the uniformity of pressure distribution on the stack surface was tested using pressure sensitive films.